1. Field of the Invention
The present invention relates to an oligomer for media to entrap microorganisms, an oligomer-polymerized hydrous gel for the media to entrap the microorganisms, and an oligomer-polymerized hydrous gel entrapping the microorganisms. More particularly, the present invention relates to an oligomer for the media to inclusively entrap the microorganisms, an oligomer-polymerized hydrous gel thereof, and an oligomer-polymerized hydrous gel entrapping the microorganisms in order to biologically treat either inorganic or organic compounds, or to treat both compounds in waste water.
2. Description of the Related Art
Biological treatment of waste water and sewage is widely employed, because the cost thereof is relatively lower than the cost treated chemically or physically. However, certain microorganisms grow slowly, or are easily poisoned. Some microorganisms hardly grow in the environment thereof. Therefore, the biological treatment is not necessarily an efficient one. In order to constructively form the environment in which the microorganisms can easily grow, a treating method in which media adhering the microorganisms on the surfaces thereof are added in waste water, or media inclusively entrapping certain microorganisms are charged in the waste water has already been put into practical use. A gel material entrapping the microorganisms needs to have characteristics to be harmless to the natural environment, not to be degenerated or decomposed by the microorganisms, to be mechanically strengthened, and to have a great capacity to entrap a lot of microorganism. As the gel material already being in practical use, Japanese Patent Application No. 60-44131 discloses a polyethylene glycol oligomer and a polyvinyl alcohol oligomer. The oligomers are polymerized to produce hydrous gel for media to entrap microorganisms. A typical oligomer construction comprises a main structure made of polyethylene glycol and polymeric double bond groups at both ends. The conventional hydrous gel for the media to entrap microorganisms made of polymerized oligomers is superior in entrapping nitrifying bacteria for treating ammonia nitrogen, so that it has been widely utilized.
Recently, kinds of environmental pollutants are increased. Biological decomposition of organochlorine substances, endocrine disrupter related substances, dioxins, and the like has been necessary. These substances are decomposed by specific microorganisms. Since a velocity of decomposition by the microorganisms is generally slow, and propagation thereof is slow, it is necessary to maintain a high concentration of the microorganisms in order to increase decomposition efficacy. One of the arts to maintain a high concentration of the microorganisms is an inclusive entrapment art in which the microorganisms are inclusively entrapped in hydrous gel.
However, there is a problem that microorganisms which decompose the endocrine disrupter related substances and the like need the hydrous gel which can entrap a higher concentration of microorganisms than that entrapped in the conventional gel.
To address the above described problem, an object of the present invention is to provide an oligomer for media to entrap microorganisms, hydrous gel polymerized the oligomers for the media to entrap the microorganisms, and the oligomer-polymerized hydrous gel entrapping the microorganisms, the oligomers having a remarkably greater capacity to entrap a lot of microorganisms, having characteristics not to be degenerated or decomposed by the microorganisms, being mechanically strengthened, and being harmless to the natural environment.
An aspect of the present invention is an oligomer comprising: a main structure made of a polyalkylene glycol; a polymeric double bond group arranged at both ends of the main structure; and a sub-structure, the sub-structure being composed of a urethane bond and an ethyleneoxy, or a urethane bond, an ethyleneoxy and a propyleneoxy, and being arranged between the main structure and the polymeric double bond groups.
According to the above described aspect of the present invention, a main structure is lengthened by inserting the sub-structures composed of urethane bonds and ethyleneoxy or urethane bonds, ethyleneoxy, and propyleneoxy between the main structure made of polyalkylene glycol and the polymeric double bond groups arranged at both ends of the main structure. In addition, the introduction of the urethane bonds causes crystallization (network formation) with the urethane double bonds themselves, so that the hydrous gel becomes flexible and the strength and the erosion resistance thereof are significantly increased. As a result, even though the main structure is lengthened to increase the capacity to entrap a lot of microorganisms, the strength of the hydrous gel does not reduce. Since the hydrophobicity of the urethane regions prevents the inclusive entrapment of the microorganisms, the hydrophobicity is weakened by ethyleneoxy.
Furthermore, hydrophobic alkyleneoxy is introduced between the ethyleneoxy straight structures at a constant ratio as the polyalkylene glycol in the above described aspect of the present invention. Thus, the decomposition of the hydrous gel by the microorganisms can be prevented by the introduction of alkyleneoxy, even though ethyleneoxy having a strong affinity for microorganisms is lengthened to increase a capacity to entrap a lot of microorganisms.
Another aspect of the present invention is an oligomer comprising a following formula,
(AAxe2x80x94O)k-Bxe2x80x94O(EO)p(PO)q-UAxe2x80x94[O(EO)m(RO)n-UA]e-O(PO)q(EO)p-Bxe2x80x94(Oxe2x80x94AA)k,
where
AA denotes an acryloyl group and a metacryloyl group;
k denotes 1 or 2;
B denotes an alkanepolyol having carbon atoms ranging from 2 to 6 except for a hydroxyl group;
EO denotes xe2x80x94CH2xe2x80x94CH2xe2x80x94Oxe2x80x94;
p denotes an integer ranging from 1 to 15;
PO denotes xe2x80x94CH2xe2x80x94CH(CH3)xe2x80x94Oxe2x80x94;
q denotes an integer ranging from 1 to 14;
UA denotes a group represented by xe2x80x94OCHNxe2x80x94Ixe2x80x94NHCOxe2x80x94, wherein xe2x80x94Ixe2x80x94 denotes an organic diisocyanate except for an isocyanate group;
m denotes an integer ranging from 20 to 100;
e denotes ranging from 1 to 2;
n denotes an integer ranging from 10 to 50; and
R denotes an alkylene group having carbon atoms ranging from 3 to 4.
Furthermore, an example of chemical structures of the oligomers which satisfy the above described conditions according to the above described aspect of the present invention is concretely shown.
Furthermore, an example of the above described chemical structure in which B denotes xe2x80x94CH2xe2x80x94CH2xe2x80x94 and xe2x80x94Ixe2x80x94 denotes isophorone group is shown.
Furthermore, the hydrous gel of the polymerized the above described oligomers allows microorganisms to adhere and grow on the surface thereof.
Furthermore, the hydrous gel according to the present invention is polymerized after mixing the oligomers and the microorganisms and can be a medium to inclusively entrap the microorganisms.